The present disclosure relates to a sense amplifier screen circuit and a screen method thereof, and more particularly to a sense amplifier screen circuit and method wherein the characteristics and sensing margin of a sense amplifier can be readily screened.
In general, sense amplifiers are classified into a bit line sense amplifier and a data bus sense amplifier. The bit line sense amplifier functions to sense and amplify data placed on a bit line and output the sensed and amplified data to a data bus, and the data bus sense amplifier functions to again sense and amplify the data amplified by the bit line sense amplifier and output the sensed and amplified data to a data output buffer.
A description will hereinafter be given of the operation of a cross coupled latch type amplifier, which is one example of such sense amplifiers.
First, when bit lines are precharged with a precharge voltage (for example, half of an internal voltage Vcore), potentials of a pair of bit lines BL and /BL are equalized to remove a voltage difference between a bit line connected to a selected memory cell and a bit line not connected thereto.
Thereafter, when a word line selected as a result of analysis of an address inputted to a row decoder is turned on, charge sharing occurs between a cell capacitance and a bit line capacitance, resulting in the generation of a potential difference between a bit line connected to a selected memory cell and a bit line not connected thereto. At this time, a potential difference between a pair of bit lines BL and /BL is amplified by the cross coupled latch type amplifier.
Notably, all sense amplifiers in cells are not uniformly operated due to factors such as process parameters. For this reason, an abnormal sense amplifier which incorrectly amplifies a potential difference between a pair of bit lines BL and /BL may be present in one cell, whereas a normal sense amplifier which correctly amplifies a potential difference between a pair of bit lines BL and /BL may be present in another cell. However, nowadays, there is no method capable of screening faulty sense amplifiers existing in cells.